1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, in particular, to a method of manufacturing a resistance element including a resistor having a thin film thickness.
2. Description of the Related Art
A manufacturing method exemplified in FIGS. 4A to 4E has conventionally been adopted for manufacturing of a resistance element used in a semiconductor integrated circuit, when a resistor has a large thickness. More specifically, first, as illustrated in FIG. 4A, a resistor 2 is processed into a desired shape on an insulating film 1. Then, as illustrated in FIG. 4B, an interlayer insulating film 3 is deposited, and contact holes are formed on the interlayer insulating film 3 by etching. Then, as illustrated in FIG. 4C, a barrier metal film 4 is formed by sputtering. Then, as illustrated in FIG. 4D, an aluminum metal film 5 is formed on the barrier metal film 4 by sputtering. Next, as illustrated in FIG. 4E, a resist pattern is formed on the aluminum metal film 5, and then the barrier metal film 4 and the metal film 5 are simultaneously etched and, after that, the resist is removed, thereby forming aluminum electrodes 10. In this way, a resistance element having electrodes provided at both ends of the resistor 2 can be formed. In a case where the resistor 2 has a small thickness a problem emerging from this method is that the contact holes may pass through the resistor 2 to thereby reduce the contact areas between the aluminum electrodes 10 and the resistor 2 when the contact holes are formed by etching in the step illustrated in FIG. 4B.
Accordingly, in the case where the resistor has a small thickness, a manufacturing method as illustrated in FIGS. 5A to 5F has been conceived. First, as illustrated in FIG. 5A, the barrier metal film 4 is formed on the insulating film 1 by sputtering. Then, as illustrated in FIG. 5B, the aluminum metal film 5 is formed on the barrier metal film 4 by sputtering. Then, as illustrated in FIG. 5C, a resist pattern is formed on the aluminum metal film 5. The barrier metal film 4 and the aluminum metal film 5 are left in a desired shape by etching and then the resist is removed, to thereby form the aluminum electrodes 10. Then, as illustrated in FIG. 5D, a resist 7 is patterned. Then, as illustrated in FIG. 5E, the resistor 2 is formed by sputtering. Then, by removing the resist 7, a resistance element in which the resistor 2 serves also as electrodes for connection can be obtained, as illustrated in FIG. 5F. In the method as illustrated in FIGS. 5A to 5F, a resistor which connects electrodes to each other may be obtained by etching without forming contact holes (see, for example, Published Japanese Patent Application No. H 06-21351).
However, in a semiconductor device described above with reference to FIGS. 5A to 5F, the metal for the interconnection has a large thickness, and thus, stress is applied to the resistor at a corner portion of the metal. As a result, disconnection may occur in a subsequent thermal process, high temperature bias test, or the like.